At the present time the progress of chemical attack on neoplasms is hindered by the inability of the therapist to deliver the cytotoxic dose to the tumor without exerting deleterious side effects such as nausea, leukepenia, thromocytopenia, diarrhea, alopecia, cirrhosis, chills and fever, ulcerative stomatitis and the like on the rest of the patient's body.
The current methods of administration of most of the available chemotherapy in use today are either oral injestion of the drug which is absorbed in the gastro intestinal tract and transported by the systemic circulation to the site of the tumor or by injection. If the drug is injected it is either by intravenous or intramuscular injection closer into the location of the neoplasm. Nevertheless the chemical agent is made available to the general blood circulation running to numerous systems and organs other than the diseased tissue. Frequently the therapeutic dose range required to necrose the tumor has harsh cytotoxic effect on the immune system of the organism at a time when the cooperation of the host defense mechanism should be brought to bear to arrest the spread of metastasis of the cancer.
Presently no known manner of direct therapeutic delivery of the many known cytotoxic agents to the tumor has been successfully implemented in part because heretofore no viable means of dissimination of the drug throughout the tissue of the neoplasm was known and in part because no means of "inerting" the cytotoxic agent until it had reached its tumor target had been disclosed. Recently considerable experimental therapy of tumors has involved radio-frequency heating of tumor masses to elevate the temperature of the tumor to levels of 41.degree. C. to as high as 50.degree. C. It has been demonstrated many times that localized hyperthermia, as it is so generally termed by oncology, can be achieved while the temperature of the surrounding normal non neoplastic tissue can be maintained at normal body temperature of 37.5.degree. C. or slightly higher in some cases but usually not over 40.degree. C. An interesting fact found from this clinical research is that the so heated tumor tissue appears to be rendered more sensitive to attack by antimetabolites such as methotrexate which interfere with the internal metabolism of the tumor cells and their DNA replication. Ruptured cell structures and partially necrosed tumor tissue enhances the dessimination of cytotoxic agents if these chemicals can be safely introduced.
What has been lacking in the art is a means of delivery of a cytotoxic agent direct to this sensitized tumor mass which will not permit attack by the cell killer or antimetabolite until it reaches its destination at the tumor tissue. This means is now available and is the subject of the present innovative method sought to be patented.